In the medical field, it is becoming increasingly common for small electrical devices to be implanted into a patient's body and dwell within to provide some therapeutic effect on an ongoing basis. For example, implanted neuroprosthetic devices may include a stimulating electrode, a computing or instruction-providing block connected to the electrode, and a power source (e.g., a battery) connected to the computing block and/or the electrode.
In some use environments, the electrode, computing block, and/or power source may be located some distance from each other because of, for example, space constraints in the area of the body being treated. Accordingly, medical providers often will provide these components in a modular format, with connecting wires of any desired length(s) linking the components into a complete system. In this manner, the components can each be located within the patient's body as desired, relatively unconstrained by available space at/near the therapeutic site.
During implantation surgery for a modular device, the surgeon places each component (electrode, computing block, power source, wire(s)) of the device into its desired position and, shortly before or after the placement, connects the components together by plugging a male connecting tip on one component into a female connecting socket on another component. This modular construction, having reversible connections, allows for custom-combined groups of components to be used for a particular patient (e.g., customized connecting wire lengths) as well as leaving open the potential of easy maintenance, upgrades, and/or replacement of components as opposed to a hard-wired, non-modular device.
Due to saline, blood, or other operating-room fluids and/or patient tissues, the components are often rather slippery and may be difficult to grasp firmly due to these extra substances and/or the position/location of the component within the body. Therefore, the surgeon wants the plug-in portion of the operation (insertion of the male connecting tip into the female connecting socket) to occur reliably with relatively low insertion force, to avoid damaging nearby body tissues or other components of the device.
However, a certain amount of retention force is needed to insure that the connection has been made firmly enough to resist inadvertent post-operative pull-out or retraction forces, such as those generated on the body tissues surrounding the components by normal movement of the patient. Accordingly, it can be difficult to balance the concurrent desires for relatively small insertion forces and relatively large retraction forces in connected-component medical devices. Currently, set screws are used to help maintain the connection. However, in the operative environment, the small size of the set screws and “envelope” of space needed to manipulate the installation tools adds unwanted complexity and inconvenience to an already difficult task.